液体表面的液滴运动在微流体和许多生物过程中具有广泛的应用前景.本文通过研究在液体基底上一种低表面张力液体对另一液体的驱动来理解Marangoni效应在自发驱动体系中的作用.为了研究液体驱动的液滴铺展过程,建立了以不易挥发性硅油作为驱动溶剂、正十六烷作为受驱动液滴,以及不同浓度的十二烷基硫酸钠溶液作为基底溶液的实验体系.通过对正十六烷液滴受驱动铺展动态过程的观察和研究,发现界面张力梯度对液体驱动的铺展起主导作用.实验结果表明:基底溶液浓度主要对正十六烷液滴的最大铺展半径存在影响.此外,用经典稳定性分析模型解释了正十六烷在受驱动铺展过程中由液柱破碎成小液滴的原因,同时得到了失稳特征参数最快不稳定波长与正十六烷液柱半径之间的关系.

Drop dynamics at liquid surfaces is existent in nature and industry, which is of great value in studying droplet self-propulsion, surface coating, and drug delivery, and possesses great potential applications in microfluidics and biological process. Here, we analyze the role of Marangoni effect in the spontaneously driving system by studying the driving effect of a low surface tension liquid at the liquid substrate on another liquid. A three-phase liquid system is established to explore the liquid-driven spreading process, including non-volatile silicone oil as driving solvent, n-hexa-12ane as driven solvent, and sodium do-12yl sulfate (SDS) solution with different concentrations as aqueous substrates. The spreading process of n-hexa-12ane driven by silicone oil can be divided into two stages. N-hexa-12ane is first driven to form a thin rim, and then the rim breaks up into small liquid beads. Afterwards, the driving mechanism, spreading scaling laws and instability characteristic parameters of the liquid-driven spreading process are analyzed theoretically. The analysis of driving mechanism indicates that the differences in surface tension among silicone oil, n-hexa-12ane and SDS solution cause surface tension gradient at the liquid-liquid interface, which plays a crucial role in spreading the n-hexa-12ane. The results also demonstrate that the maximum spreading radius of n-hexa-12ane is affected by the concentration of the aqueous substrate. When the concentration of SDS solution is lower than the critical micelle concentration, the maximum spreading radius of n-hexa-12ane is proportional to the concentration of SDS solution. Meanwhile, the scaling law between the spreading radius R and time t driven by silicone oil conforms to the classical theoretical. In addition, the classical analysis model is used to explain the instability pattern of n-hexa-12ane breaking into small beads from rim in the liquid-driven spreading process, which is called Rayleigh-Plateau instability. The fastest instability wavelength and the constant radius of the nhexa-12ane liquid rim are related by. Our results prove the applicability of the spreading scaling law to the liquid-driven spreading process, and also help to understand in depth the mechanism of the liquid-driven spreading and the instability pattern in the spreading process.